Cyber Resilience

CVE-2025-12084

DoS in Python ≤ 3.13.11

Published
03 December 2025
Modified
26 January 2026
Patch / advisory
CVSS Score v4 6.3
Click a component to see what it means
Raw vectorCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS Score 0.0078 53th percentile
Risk Priority 41 floored blend · peak EPSS

Summary

CVE-2025-12084 is a medium-severity Inefficient Algorithmic Complexity (CWE-407) vulnerability in Python Python. Its CVSS base score is 6.3 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Endpoint Denial of Service (T1499); ranked in the top 47% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to SC-5 (Denial-of-service Protection) and SC-6 (Resource Availability) — see the control section below for these in your framework.

EU & UK References

Vulnerability Data

When building nested elements using xml.dom.minidom methods such as appendChild() that have a dependency on _clear_id_cache() the algorithm is quadratic. Availability can be impacted when building excessively nested documents.

CWE(s)

Related Threats

MITRE ATT&CK Enterprise Techniques

T1499 Endpoint Denial of Service Impact
Adversaries may perform Endpoint Denial of Service (DoS) attacks to degrade or block the availability of services to users.
T1499.003 Application Exhaustion Flood Impact
Adversaries may target resource intensive features of applications to cause a denial of service (DoS), denying availability to those applications.
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2024-6232Same product: Python Python
CVE-2026-4224Same product: Python Python
CVE-2023-36632Same product: Python Python
CVE-2025-13837Same product: Python Python
CVE-2024-7592Same product: Python Python
CVE-2025-13836Same product: Python Python
CVE-2026-15308Same product: Python Python
CVE-2025-6075Same product: Python Python
CVE-2026-4360Same product: Python Python
CVE-2026-4519Same product: Python Python

Affected Assets

python
python
3.15.0 · ≤ 3.13.11 · 3.14.0 — 3.14.2

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

Detect
Catch it (NIST detect / respond)

Harden
Shrink the surface (DISA STIG)

Validate
Prove the fix (OWASP ASVS)
  • V1.2.9

Mitigating Controls (NIST 800-53 r5) AI

Denial-of-service protection directly reduces the impact of resource exhaustion triggered by worst-case algorithmic inputs.

Resource availability allocation limits blast radius when an inefficient algorithm is forced into its worst case.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure SDLC practices (code review, complexity analysis, safe algorithm selection) prevent introduction of exploitable worst-case behavior.

DE.CM-09 partial match
prevents

Runtime monitoring of software and resources can detect the performance impact of triggered worst-case complexity.

ID.RA-01 partial match
prevents

Identifying and recording algorithmic-complexity vulnerabilities directly addresses the root cause before exploitation.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

finds

Security testing can uncover performance issues stemming from algorithmic complexity.

mitigates

Redundancy of processing facilities can absorb resource exhaustion from inefficient algorithms.

finds

Monitoring activities can identify anomalous resource consumption indicative of algorithmic complexity attacks.

prevents

Secure development life cycle includes design reviews that can catch inefficient algorithms before deployment.

prevents

Secure system architecture principles encourage selection of algorithms with acceptable worst-case complexity.

prevents

Secure coding practices can include guidelines to avoid or mitigate inefficient algorithms.

References